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Here's a brief look at the Minolta AF 24mm F/2.8 lens.
Scroll down for the review.
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Lens
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Minolta AF 24mm F/2.8
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Box contents
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Front and rear caps, hood and users manual.
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Cost
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$150-$250 used on eBay
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Build quality
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Very good
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Additional information
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Full frame and no Sony equivalent yet.
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Specifications below
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Optical configuration
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8 elements in 8 groups
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Angle of view
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84° full frame, 56° APS-C.
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Aperture
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7 blades, straight
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Full frame and APS-C
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Yes, made for full frame. APS-C equivalent, 36mm
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Depth of field and focus scales?
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Yes and yes
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Minimum focus, image plane to subject
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10" (254mm)
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Minimum focus, end of lens barrel to subject
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6" (152mm)
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Hard stop at infinity focus?
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Yes
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Length changes when focusing?
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No
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Focus ring turns in AF?
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Yes
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Filter size
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55mm
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Filter ring rotates?
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No
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Distance encoder?
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No
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Max magnification
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0.16x
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Min. F/stop
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F/22
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Sony teleconverter compatible?
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No
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Dimensions W x L (my measurements)
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2.6" x 1.7" 66mm x 44mm
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Maximum extended length (my measurements)
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1.7" (44mm)
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Weight bare (my scale)
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7.5oz (211g) 8.2oz (233g) with caps
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Requisite product shots.
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| Side shot |
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| Front element much larger than 28mm F/2.8 |
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| Side shot with original hood. |
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| Rear view |
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| Left 28mm, right 24mm. |
All testing done with the Sony A 700 and A900. For full frame results, go to the bottom of the page. For a better understanding of my
review methods and terminology, go here. This page has a copy of the orignal owner's manual. The Minolta AF 24mm F/2.8 is a compact lens,
about as small as you're going to get. Externally, it's nearly identical to the Minolta 28mm F/2.8, the only thing different
is the larger front element on the 24mm lens. Build quality is very good. This model is from the original
1985 design. It has a satin black finish with white index marks along the focus distance window. It also has an
Infra-red focus index, the red dot on the aperture scale. The lens says "Japan" so I'm assuming it's made
in Japan. Focusing is quick and accurate, especially with the Sony A700. Manual focusing is a chore, since the
ring is slightly stepped down at the end of the barrel, plus the ring is very narrow and hard to manipulate with your
fingers.
The lens is multi-coated with the mild magenta/green look. The same as most
other Minolta lenses from this era. Filter size is 55mm.
Sharing this size in the Sony lineup are: 50mm F/1.4, 50mm F/2.8 macro, 55-200mm, 100mm F/2.8 macro, 75-300mm, 35mm F/1.4
and the 18-70 kit lens. Filter use. Regular filters cause no additional
vignetting on full frame or APS-C cameras.
Lateral color fringing. I see some red fringing
on the sides. Stopping down doesn't help, but it's not really noticeable unless you look at your pictures
at 100%. Very similar to the 28mm F/2.8 lenses. Average control here.
Bokeh.
Depends, close at F/2.8, a little harsh, stopped down to F/4-5.6 it's smoother, without the donuts. Longer subject to
background distances look good. See crops below.
Color looks nearly
the same as other Minolta/Sony lenses. Coma. Strong at F/2.8, better
at F/4 and nearly gone at F/5.6. Flare and ghosting. With the sun inside
the frame, you'll see several blobs, followed by a golden arrow or two, depending on angle. Similar to the Minolta 28mm
F/2.8 lens. The supplied hood really doesn't do much, use your hand for best results with the sun outside the image.
See images below.
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Sun centered, F/5.6
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Sun in shot, F/5.6
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Bokeh, F/2.8
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Bokeh, F/4
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The top shots show what happens when you have the sun in the shot. This lens holds up well to
ghosting and flare. There is very little flare with the sun just outside the frame, good control here. When the
sun is centered, left image, everything looks great. With the sun offset, you'll get a few small blobs of color
opposite the sun, and a retrograde ghost, (blob on the other side of the sun). Overall, the lens performed well here.
Bokeh examples on the bottom. The F/2.8 shot looks busy, the F/4 shot is smoother,
but you can see some heptagons from the straight bladed aperture occasionally in harsh, bright backgrounds.
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| Barrel distortion. |
Light fall-off below.
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F/2.8
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F/4
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light fall off or corner shading is well controlled on this lens. On
an aps-c size sensor there is a mild amount at F/2.8, but it's very gradual, and blends nicely towards the center
making it nearly invisible in real world pictures. I gets better as you stop down. The picture for the
corners below shows light fall-off at F/2.8.
Next, we have the corner sharpness sample frame
crops. Go below to read the results.
This is the overall view of the corner crops below, above shot at F/2.8.
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F/2.8
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F/4.0
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F/5.6
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F/8
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The corners sharpen up nicely as you stop the lens down. The corners are pretty sharp at F/5.6 and beyond.
Don't worry about soft corners at F/2.8, you wouldn't be using F/2.8 in daylight anyways, and in low light it won't
show, so it's really not a problem.
Center sample results. Read below.
This is the entire scene of the sample center shots below.
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F/2.8
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F/4
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F/5.6
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F/8
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F/11
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Above, look at the ridiculously boring pictures trying to split hairs on sharpness. At F/2.8, it's
pretty sharp, but not the sharpest, which I think is at F/4-F/8, then a slight softening at F/11. Keep in mind the sample
crops are enlarged here to 100%, much larger than most people would normally observe. Under normal circumstances,
you'll never see any soft centers. There might be a bit less contrast at F/2.8 which can make it appear less sharp. Below, check out the close focus sample. Click to see a 100% cropped portion of the full image, 175kb.
The sample shot was taken with the Sony A 700 12.2mp camera. The subject is a standard US stamp, 1"x 3/4" or 25.4mm x 19mm. Also, note the macro
shot was taken as close to the subject as focusing allowed; In this case, about 6" or 152mm, measured from the front
of the lens barrel to the subject.
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| F/5.6, click for larger image. 175kb |
This doesn't have much in the way of a macro ability, and you shouldn't expect it to. It is sharp
though. I also see some moire, so don't shoot patterns like this from 6" (152mm) away. If you want a
good macro on a lens with low magnification, use a close up filter like I did here.
Full frame results using the Sony A900 below. Check out
the differences when using a film or full frame camera below. I'm only pointing out the noticeable issues as compared
to the APS-C bodies, so if I don't show it here, the results are not significantly different enough to warrant posting
an additional set of images in this section. Light fall-off
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F/2.8
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F/4
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Light fall-off is worse than the APS-C crops shown earlier. At F/2.8 it's heavy, and noticeable
in real shots, but one stop down and things change dramatically for the better. It doesn't get much better by stopping
down past F/4. Full image from A900 below. The dark corners are not very noticeable here, then again this example isn't the best. This shot
was F2.8, ISO 200, 1/3200sec. As always, don't shoot normal daylight shots wide open. Corner samples next.
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F/2.8
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F/4
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F/5.6
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F/8
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F/11
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F/16
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The corners are softer than the APS-C crops show. Don't sweat this too much as a normal
landscape shot would be at least F/5.6, and low light shots would probably hide soft corners depending on subject matter.
F/8 looks good, though It does appear F/11 produces the sharpest corners, but not by much. F/16 is not needed as it
is no sharper. The exposure differences are from light fall-off. Distortion.
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| Barrel distortion on A900 |
There is slightly more barrel distortion, but the only way to notice it is to toggle between the two
images. Coma results with full frame.
This is coma on the A900. It's heavy at F/2.8, but clears up quite a bit at F/4. I wouldn't
be afraid to shoot night time street scenes at F/4, but if you use F/2.8, make sure you try and keep points of light away
from the corners, otherwise, you may have a messed up shot. Keep in mind the images above are 100% (corner cropped)
portions of the whole image, and printed out as you might see it on your computer screen would measure 65" (1.9m) wide
using the A900.
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Conclusion
The Minolta AF 24mm F/2.8 lens turned in a pretty good performance. It's
fairly sharp at F/2.8, and sharp at F/4 to F/8. The corners are soft at F/2.8, but that's no big deal as stated above.
It's more useful than the 28mm on an APS-C camera; equaling 36mm, which is a nice walk around focal length in my opinion,
better than the 42mm equivalent of the 28mm. Current prices are running around $150-$200 on eBay, which is an excellent
bargain if you can live within the focal length. This lens will deliver sharp shots at F/2.8, for those that look at
their images at 100% all day, use F/4.
Full frame users will notice some
soft corners unless stopped down to F/8, and some heavy coma wide open, so watch the street scenes at night. This is
a good lens, and provides a small, light package compared to the zoom lenses starting at 24mm. I'm not sure you're really
getting much else though, as the overall results aren't much different than the Sony 24-105mm, though that lens starts at F/3.5, which is just 2/3 of a stop more. I guess if you need a small, inexpensive wide
angle lens of this focal length, it makes sense. I'd be willing to trade 2/3 of a stop of light and the portability
of a prime lens for the convenience of a zoom lens, that's just me. Update; this
lens is not so impressive when comparing it to the modern Sony CZ 24-70mm F/2.8 zoom. The Minolta 24mm prime lacks contrast,
and isn't as sharp all around as the CZ at 24mm, but the prime does better at controlling ghosting.
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